In general, various methods are being used in constructing a tunnel used for roads or railways. Hard bedrock is generally destructed using explosives and is excavated using excavation equipment.
With the recent development of large-scale equipment called a tunnel boring machine (TBM), tunnels have been constructed without using explosives. In the TBM based tunnel construction, an excavation work is carried out on a circular cross-section, which is a mechanically stable, vibration-free, non-blasting method. Thus, the TBM based tunnel construction may be an environmentally friendly tunnel excavation method, that is, ground deformation due to a ground excavation is minimized, thereby securing maximized stability during construction by ground excavation. In addition, environmental damages due to noise and vibration can be minimized, thereby maintaining tunnel working conditions in a safe and clean state.
The above tunnel excavation device is capable of excavating the entire cross-section of a tunnel by rotating a disk-shaped excavation head with a bit, a cutter, etc. attached thereto, or freely excavating a required cross-section of a tunnel by freely moving a drum with a bit, a cutter, etc. attached thereto. The above tunnel excavation device is particularly effectively used when a tunnel is constructed in a relatively hard ground, like in a mountainous area.
Meanwhile, the conventional tunnel excavation device is proposed in Korean Utility Model Registration No. 0368000, which relates to a non-vibration tunnel excavator. The proposed tunnel excavator comprises: a central shaft having a central core drill provided at a front end thereof for perforating a central groove in a rock surface when rotated by a driving means, and having a piston rotatably coupled to a lengthwise middle part thereof through a slide sheet for moving the central shaft forward and backward; a cylinder member to which the central shaft is rotatably coupled, the cylinder member having a slide space in which a piston is slidably inserted and can be moved forward and backward with a predetermined range according to a hydraulic pressure to move the central shaft forward and backward; an outer core groove perforating member being rotated together with the central shaft, the outer core groove perforating member having a rotating plate fitted integrally into a front drill assembling part of the central shaft through a central part thereof, a core pipe coupled to the edge of the rotating plate and protruded forward as long as a length of the central core drill, a cutting bite combined with the front edge of the core pipe for forming a core groove, and at least one operator-guiding hole formed on a circumference of the rotating plate for allowing an operate to pass therethrough; a support member combined with an outer part of the cylinder member and selectively fixed to an inner wall of a hole via a plurality of jacks which are positioned on the inner wall of a hole formed by the outer core groove perforating member to then be provided to the exterior part; at least one crushing core drill member detachably coupled with the rotating plate of the outer core groove perforating member, and having a core drill provided at a front end thereof and rotated by the driving means; and a control unit controlling components of the above members when power is applied.
However, the tunnel excavation device disclosed in the above registered utility model has poor excavation efficiency because a plurality of grooves are formed on a surface of the bedrock by means of the central core drill and a plurality of core drills for tunnel excavation and then crushed immediately. In addition, the device disclosed in the above utility model does not effectively prevent a shortening of life span caused by abrasion of outer core groove perforating member and various types of cutters.